The Roads and Maritime Services have an incident reporting number 13 17 00, option 5, where you can report a road hazard.

Note that 80% of roads are the responsibility of local councils, so unless you are certain it is a State road looked after by the RMS, it may be better to report it to the Local Council.

It is also a good idea to report it to the Motorcycle Council as this could assist a fellow rider getting compensation should the hazard cause them to crash.